Constant force syringe

ABSTRACT

Various syringe systems are disclosed. One such syringe system may include a body having a hollow lumen and a distal end, a vacuum chamber disposed within the hollow lumen of the syringe body, a first plunger connected to a distal portion of the vacuum chamber, the first plunger forming a first seal against an inner surface of the syringe body and defining a fluid volume between the first plunger and the distal end of the syringe body, a second plunger disposed within the vacuum chamber, the second plunger forming a second seal against an inner surface of the vacuum chamber and defining proximal and distal volume compartments within the vacuum chamber, and a piston affixed to the second plunger, the piston configured to move the second plunger within the vacuum chamber, thereby altering a volume of the proximal volume compartment and a volume of the distal volume compartment.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. application Ser. No.13/797,959, filed Mar. 12, 2013, entitled “Constant Force Syringe”, thedisclosure of which is hereby incorporated by reference it its entirety.

BACKGROUND OF THE DISCLOSURE

1. Field of the Disclosure

The present application relates, in general, to a syringe, and, inparticular, to a constant force syringe for administration andaspiration of medications, supplements, fluids, contrast media, and/orthe like at a constant rate.

2. Description of the Related Art

During various medical procedures, it may be necessary to administerand/or aspirate medications, supplements, fluids, contrast media,saline, and/or the like to and from a patient or a fluid container. Ingeneral, administration and aspiration may occur subcutaneously,intramuscularly, intraperitoneally, and/or intravenously. In someinstances, administration may be accomplished with the use of a manuallyactivated syringe. In other instances, administration and/or aspirationmay occur to and from a fluid container.

Occasionally, a constant rate of administration or aspiration may be ofparticular concern to the medical services provider and/or the patient.In an illustrative example, biological cells included in some treatmentsmay be susceptible to damage if the pressure (or vacuum) and/or the flowrate of the injection/aspiration is too high. Furthermore, damage to thebiological cells may reduce the efficacy of treatment. In anotherillustrative example, the rate of delivery/aspiration may be importantto ensure proper uptake of an agent. Even the most skilled medicalservices provider may struggle with the process of smoothlyadministering/aspirating at a constant rate.

Cells are sensitive to shear forces and turbulence generated during acollection procedure. Non-constant rate or a rate above a cell lysisthreshold can cause the rupture or the destruction of the cells. Whenthe cell structure is compromised in this manner, a collected fluidspecimen may not be identical to the fluid in the environment from whichit is collected.

Previous attempts to ensure smooth administration and/or aspiration ofmedications, supplements, fluids, contrast media, and/or the like at aconstant rate have resulted in injector systems that are used toadminister and/or aspirate a fluid at a constant rate that arecomplicated and expensive to use and implement.

SUMMARY OF THE DISCLOSURE

In an embodiment, a syringe system may include a syringe body having ahollow lumen and a distal end. The syringe body may be configured toreceive a fluid therein. A vacuum chamber may be disposed within thehollow lumen of the syringe body. A first plunger may be connected to adistal portion of the vacuum chamber within the hollow lumen of thesyringe body. The first plunger may form a first seal against an innersurface of the syringe body and define a fluid volume between the firstplunger and the distal end of the syringe body. A second plunger may bedisposed within the vacuum chamber. The second plunger may form a secondseal against an inner surface of the vacuum chamber and define aproximal volume compartment and a distal volume compartment within thevacuum chamber. A vent may be provided within one of the proximal volumecompartment and the distal volume compartment of the vacuum chamber. Thevent may be configured to allow communication of air between an areaoutside the syringe system and one of the proximal volume compartmentand the distal volume compartment. A piston may be affixed to the secondplunger and extend proximally out of the vacuum chamber. The piston maybe configured to move the second plunger within the vacuum chamber,thereby altering a volume of the proximal volume compartment and avolume of the distal volume compartment.

In another embodiment, the vent may include a bore extendingtherethrough the piston and the second plunger, where the bore isconfigured to allow communication of air between an area outside thesyringe system and one of the proximal volume compartment and the distalvolume compartment. A valve may be provided to regulate an amount of theair communicated between the area outside the syringe system and one ofthe proximal volume compartment and the distal volume compartment. Thevent may include a side vent extending through a wall in one of theproximal volume compartment and the distal volume compartment of thevacuum chamber. The side vent may be configured to allow communicationof air between an area outside the syringe system and one of theproximal volume compartment and the distal volume compartment.

In another embodiment, a tip may be provided at the distal end of thesyringe body. The tip may be configured to allow fluid from the fluidvolume to pass therethrough upon movement of the first plunger. The tipmay be further configured to attach to one or more tubes, needles, ornozzles for delivery of the fluid to a patient. The piston may extendproximally out of the vacuum chamber through a proximal wall, forming athird seal between the piston and the proximal wall.

In another embodiment, a force exacted upon the piston in asubstantially distal direction may be configured to cause the secondplunger to move distally within the vacuum chamber, thereby increasingthe volume of the proximal volume compartment and decreasing the volumeof the distal volume compartment, creating a pressure difference betweenthe proximal volume compartment and the distal volume compartment, whichcauses the vacuum chamber and the first plunger to move in a distaldirection, thereby expelling the fluid located in the fluid volume outof a tip in the distal end of the syringe body. Alternatively, a forceexacted upon the piston in a substantially proximal direction may beconfigured to cause the second plunger to move proximally within thevacuum chamber, thereby increasing the volume of the distal volumecompartment and decreasing the volume of the proximal volumecompartment, creating a pressure difference between the proximal volumecompartment and the distal volume compartment, which causes the vacuumchamber and the first plunger to move in a proximal direction, therebyaspirating the fluid into the fluid volume through a tip in the distalend of the syringe body.

In another embodiment, a syringe system may include a syringe bodyhaving a hollow lumen and a distal end. The syringe body may beconfigured to receive a fluid therein. A vacuum chamber may be at leastpartially disposed within the hollow lumen of the syringe body. A firstplunger may be disposed distally to the vacuum chamber within the hollowlumen of the syringe body. The first plunger may form a seal against aninner surface of the syringe body and define a fluid volume between thefirst plunger and the distal end of the syringe body. A second plungermay be disposed within the vacuum chamber to define a proximal volumecompartment and a distal volume compartment within the vacuum chamber. Aside vent may extend through a wall in one of the distal volumecompartment and the proximal volume compartment of the vacuum chamber.The side vent may be configured to allow communication of air between anarea outside the syringe system and one of the proximal volumecompartment and the distal volume compartment. A piston may extenddistally out of the vacuum chamber and connect to the first plunger andthe second plunger. The piston may be configured to move the secondplunger within the vacuum chamber and the first plunger within thesyringe body.

In another embodiment, a tip may be provided at the distal end of thesyringe body. The tip may be configured to allow fluid from the fluidvolume to pass therethrough upon movement of the first plunger. The tipmay be further configured to attach to one or more tubes, needles, ornozzles for delivery of the fluid to a patient.

In another embodiment, a force exacted upon the vacuum chamber in asubstantially distal direction may be configured to cause the vacuumchamber to move distally within the syringe body, thereby decreasing thevolume of the proximal volume compartment and increasing the volume ofthe distal volume compartment, creating a pressure difference betweenthe proximal volume compartment and the distal volume compartment, whichcauses the second plunger, the piston, and the first plunger to move ina distal direction, thereby expelling the fluid located in the fluidvolume out of a tip in the distal end of the syringe body.Alternatively, a force exacted upon the piston in a substantiallyproximal direction may be configured to cause the second plunger to moveproximally within the vacuum chamber, thereby increasing the volume ofthe distal volume compartment and decreasing the volume of the proximalvolume compartment, creating a pressure difference between the proximalvolume compartment and the distal volume compartment, which causes thevacuum chamber and the first plunger to move in a proximal direction,thereby aspirating the fluid into the fluid volume through a tip in thedistal end of the syringe body.

In yet another embodiment, a syringe system may include a syringe bodyhaving a hollow lumen and a distal end having a tip. The syringe bodymay be configured to receive a fluid therein. A vacuum chamber may be atleast partially disposed within the hollow lumen of the syringe body. Afirst plunger may be disposed distally to the vacuum chamber within thehollow lumen of the syringe body and form a seal against an innersurface of the syringe body, thereby defining a fluid volume between thefirst plunger and the distal end of the syringe body. A second plungermay be disposed within the vacuum chamber, the second plunger defining aproximal volume compartment and a distal volume compartment within thevacuum chamber. A piston may extend distally out of the vacuum chamberand be connected to the first plunger and the second plunger. The pistonmay be configured to move the second plunger within the vacuum chamberand the first plunger within the syringe body.

In another embodiment, a thumb piece may be removably attached to aproximal portion of the vacuum chamber. The thumb piece may beconfigured to provide a surface for a user to apply a force in asubstantially axial direction. The thumb piece may be further configuredto increase and decrease a volume of one of the distal volumecompartment and the proximal volume compartment. The thumb piece may beconfigured to increase and decrease the volume of one of the distalvolume compartment and the proximal volume compartment by screwing intoat least a portion of the vacuum chamber. The thumb piece may beconfigured to move in a distal direction, wherein the vacuum chamber isconfigured to move within the syringe body in response to movement ofthe thumb piece. The second plunger, the piston, and the first plungermay be configured to move in response to the vacuum chamber movingwithin the syringe body.

In another embodiment, a syringe system may include a syringe bodyhaving a hollow lumen and a distal end having a tip. The syringe bodymay be configured to receive a fluid therein. A vacuum chamber may be atleast partially disposed within the hollow lumen of the syringe body. Afirst plunger may be disposed distally to the vacuum chamber within thehollow lumen of the syringe body. The first plunger may form a sealagainst an inner surface of the syringe body and define a fluid volumebetween the first plunger and the distal end of the syringe body. Asecond plunger may be disposed within the vacuum chamber. The secondplunger may define a proximal volume compartment and a distal volumecompartment within the vacuum chamber. A thumb piece may be configuredto screw into a proximal portion of the vacuum chamber. The thumb piecemay be configured to increase and decrease a volume of one of the distalvolume compartment and the proximal volume compartment. A piston mayextend distally out of the vacuum chamber and be connected to the firstplunger and the second plunger. The piston may be configured to move thesecond plunger within the vacuum chamber and the first plunger withinthe syringe body. A guide may be provided on an outside surface of thevacuum chamber, such that the guide is configured to assist a user ofthe syringe system to screw the thumb piece to a desired depth in thevacuum chamber to ensure a desired volume of one of the distal volumecompartment and the proximal volume compartment. The thumb piece may befurther configured to increase and decrease a flow rate of the fluid outof the syringe system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A depicts a side view of a syringe having a vent according to anembodiment.

FIG. 1B depicts a side view of a syringe having an angled bore accordingto an embodiment.

FIG. 1C depicts a side view of a syringe having a bore that extendsthrough the thumb piece according to an embodiment.

FIG. 2A depicts a side view of an alternative syringe having a side ventaccording to an embodiment.

FIG. 2B depicts a side view of an alternative syringe having a screw-onthumb piece according to an embodiment.

FIGS. 3A-3B depict movement of the various components of the syringedepicted in FIG. 1A according to an embodiment.

FIGS. 4A-4C depict movement of the various components of the syringedepicted in FIG. 2A according to an embodiment.

FIGS. 5A-5C depict movement of the various components of the syringedepicted in FIG. 2B according to an embodiment.

FIG. 6A depicts a side view of a syringe having a vent according to anembodiment.

FIG. 6B depicts a side view of a syringe having an angled bore accordingto an embodiment.

FIG. 6C depicts a side view of a syringe having a bore that extendsthrough the thumb piece according to an embodiment.

FIG. 7A depicts a side view of an alternative syringe having a side ventaccording to an embodiment.

FIG. 7B depicts a side view of an alternative syringe having a screw-onthumb piece according to an embodiment.

FIGS. 8A-8B depict movement of the various components of the syringedepicted in FIG. 6A according to an embodiment.

FIGS. 9A-9C depict movement of the various components of the syringedepicted in FIG. 7A according to an embodiment.

FIGS. 10A-10C depict movement of the various components of the syringedepicted in FIG. 7B according to an embodiment.

DETAILED DESCRIPTION OF THE DISCLOSURE

This disclosure is not limited to the particular systems, devices andmethods described, as these may vary. The terminology used in thedescription is for the purpose of describing the particular versions orembodiments only, and is not intended to limit the scope.

As used in this document, the singular forms “a,” “an,” and “the”include plural references unless the context clearly dictates otherwise.Unless defined otherwise, all technical and scientific terms used hereinhave the same meanings as commonly understood by one of ordinary skillin the art. Nothing in this disclosure is to be construed as anadmission that the embodiments described in this disclosure are notentitled to antedate such disclosure by virtue of prior disclosure. Asused in this document, the term “comprising” means “including, but notlimited to.”

For purposes of the description hereinafter, the terms “upper,” “lower,”“right,” “left,” “vertical,” “horizontal,” “top,” “bottom,” “lateral,”“longitudinal,” and derivatives thereof shall relate to the orientationof embodiments disclosed in the figures. However, embodiments may assumealternative variations and step sequences, except where expresslyspecified to the contrary. The specific devices and processesillustrated in the attached drawings and described in the followingspecification, are exemplary embodiments. Hence, physicalcharacteristics related to the embodiments disclosed herein are not tobe considered as limiting.

The word “proximal” refers to a direction relatively closer to aclinician or operator using the device described herein, and the word“distal” refers to a direction relatively further from the clinician oroperator. For example, the end of a syringe placed nearest the body of apatient is considered a distal end of the syringe, while the end closesto the clinician is a proximal end of the syringe. The terms “axial” or“axially” refer generally to an axis around which the particular objectsbeing referred to are preferably formed (although not necessarilysymmetrically therearound). The term “radial” refers generally to adirection normal to the axis or along a radius of an object having acircular cross-section.

Various embodiments of the present disclosure may be directed tosyringes, particularly those used for manual fluid delivery andaspiration, that may rely on a transient vacuum induced within one ormore compartments of the syringe. In some embodiments, the fluid may bedelivered from the syringe at a uniform rate because the vacuum itselfpowers the fluid delivery or aspiration, as applicable, instead of theperson or device pressing on the thumb piece of the syringe.

FIG. 1A depicts a side view of a syringe, generally designated 100,having a vent 135 according to an embodiment. The syringe 100 maygenerally include a syringe body 105 having a hollow lumen 107, aproximal end 101, and a distal end 102 having a tip 110. The syringebody 105 is not limited in shape or size by this disclosure, and may beany shape or size, particularly shapes and sizes of syringe bodiescommonly known by those skilled in the art. In various embodiments, thesyringe body 105 may be substantially cylindrical. In variousembodiments, the syringe body 105 may be about 4 ml to about 20 ml involume. In particular embodiments, the volume of the syringe body 105may be about 4 ml, about 5 ml, about 10 ml, about 15 ml, about 20 ml, orany value or range between any two of these values. In variousembodiments, the syringe 100 may be made of glass, a polymer, and/or thelike.

In various embodiments, the hollow lumen 107 may include a plurality ofplungers disposed therein. For example, in the present embodiment, thehollow lumen 107 may have a first plunger 125 and a second plunger 150.However, those skilled in the art will recognize that more than twoplungers may be used without departing from the scope of thisdisclosure. In some embodiments, a vacuum chamber 120 may be disposedwithin the syringe body 105 in contact with the first plunger 125. Invarious embodiments, the first plunger 125 may form a seal against theinterior of the syringe body 105 by means of a first seal 130. In someembodiments, the first seal 130 may be a separate component from thefirst plunger 125, such as, for example, an added O-ring and/or thelike. In these embodiments, the first seal 130 may be fixedly attachedto the first plunger 125 by any means of attachment, includingattachment apparatuses, adhesives, and/or the like, or the first sealmay removably attached to the first plunger. In other embodiments, thefirst seal 130 may be fabricated as a portion of the first plunger 125.In some embodiments, the first seal 130 may be associated with a distalportion of the vacuum chamber 120.

In various embodiments, the second plunger 150 may be disposed withinthe vacuum chamber 120. In some embodiments, the second plunger 150 maybe mechanically activated by a piston 155. The second plunger 150 may beattached to the piston 155 by any means of attachment, including, butnot limited to, any number of clips, fasteners, hooks, adhesives, and/orthe like. In some embodiments, the second plunger 150 may be molded as aportion of the piston 155. In some embodiments, the piston 155 may atleast partially extend out of an opening of the proximal end 101 of thesyringe body 105. In some embodiments, the piston 155 may generallyextend out of the vacuum chamber 120 through a proximal wall 140. Theopening in the proximal wall 140 may be sealed with a second seal 145 tothe piston 155. The second seal 145 may be an air-tight seal around theshaft of the piston 155. In some embodiments, in lieu of the vent 135,the piston 155 may contain a bore therethrough, such as 180 in FIG. 1Bor 180′ in FIG. 1C, as described in greater detail herein.

In various embodiments, a proximal portion of the piston 155 may beconnected to a thumb piece 160. The thumb piece 160 may generallyprovide a surface upon which a user's digits or another device applies aforce to move the piston 155 in either a distal or proximal direction.The thumb piece 160 depicted herein is a generally flat surface;however, those skilled in the art will recognize that the shape and sizeof the thumb piece is not limited by this disclosure, and may includeany number of rings, openings, contoured surfaces, and/or the likewithout departing from the scope of the present disclosure. Personsskilled in the art will also note that the term ‘thumb piece’ is notintended to be limiting; while a thumb may be a preferred digit formanipulating the thumb piece 160, the user may use any object tomanipulate the thumb piece as described herein. In an illustrativeexample, a user may press his/her thumb against the thumb piece 160 toeffect distal movement of the piston 155 and/or other components of thesyringe 100, as described in greater detail herein.

Similar to the first plunger 125 described herein, in variousembodiments, the second plunger 150 may form an airtight seal against aninterior surface of the vacuum chamber 120, thereby dividing the vacuumchamber into two volume compartments. A distal volume compartment 165may be created by the space between a distal surface of the secondplunger 150 and a proximal end of the first plunger 125. A proximalvolume compartment 170 may be created by the space between a proximalsurface of the second plunger 150 and a distal surface of the proximalwall 140 of the vacuum chamber 120.

In various embodiments, the vacuum chamber 120 may be detachable fromthe first plunger 125. The ability to detach the vacuum chamber 120 fromthe first plunger 125 may allow for use of vacuum chambers that vary insize and shape, thereby increasing compatibility with a wide range offorces to allow for varying pressures and flow rates, as described ingreater detail herein.

In various embodiments, the vacuum chamber 120 may include a vent 135.The vent 135 may generally be an opening within the vacuum chamber toallow fluid communication of air between the distal volume compartment165 and an area outside the syringe body 105. In some embodiments, thecommunication between the vent 135 and the area outside the syringe body105 may be along a path bounded by the inner surface of the syringe bodyand the outer surface of the vacuum chamber 120.

In various embodiments, a fluid delivery volume 175 may be definedwithin the syringe body 105. In some embodiments, the fluid deliveryvolume 175 may be defined as the space that is located distally to thefirst plunger 125. In some embodiments, the fluid delivery volume 175may contain a fluid therein. Examples of fluids are not limited by thisdisclosure, and may include, for example, medications, supplements,bodily fluids, contrast media, saline, and/or the like. In someembodiments, fluid contained within the fluid delivery volume 175 may bedelivered through the tip 110. The tip 110 may further be configured tobe connected to additional elements, such as, for example, needles,tubes, nozzles, and/or the like for delivery of the fluid. It may beappreciated that the first seal 130 may be configured to prevent airtransfer from either outside the syringe body 105 or the vacuum chamber165 from entering the delivery volume 175. Similarly, the first seal 130may be configured to prevent air and/or fluid from escaping the deliveryvolume 175 into the vacuum chamber 165 and/or the remainder of thesyringe body 105. The volume of the delivery volume 175 may bedetermined by the distance between the first plunger 125 and the distalend 102 of the syringe body 105, as well as the circumference of thesyringe body.

In various embodiments, one or more finger guards 115 may be positionedat a location that is generally located at or near the proximal end 101of the syringe body 105. In some embodiments, the finger guards 115 maygenerally be located on an outside surface of the syringe body 105 andmay generally extend from the outside surface of the syringe body. Insome embodiments, the finger guards 115 may act to provide stability tothe syringe 100 during operation. In some embodiments, a user may usethe finger guards 115 to prevent movement of the syringe 100 duringoperation. In some embodiments, the user may use the finger guards 115to prevent the syringe 100 from slipping out of the user's hand. In someembodiments, the user may use the finger guards 115 to protect theuser's fingers. In some embodiments, the finger guards 115 may act as astopping device to prevent the piston 155 from moving further distallyinside the syringe body 105. The shape and size of the finger guards 115are not limited by this disclosure, and may be any shape and/or sizeknown in the art. Specific examples of shapes may be ring shaped, wedgeshaped, and/or the like.

In various embodiments, as depicted in FIGS. 1B and 1C, the bore 180,180′ may be used in lieu of the vent 135 (FIG. 1A). In some embodiments,the bore 180, 180′ may extend through at least a portion of the piston155 and/or the second plunger 150. In some embodiments, the bore 180,180′ may be configured to allow air from outside the syringe 100 toenter and/or escape the vacuum chamber 120, effectively regulating byincreasing and/or decreasing the pressure of air inside the vacuumchamber. In some embodiments, the bore 180 may include a bore outlet 181containing a valve and/or the like to assist in regulation of airpressure inside the vacuum chamber 120. In some embodiments, the valvemay be incorporated within the thumb piece 160. In other embodiments,the valve may be a separate element, such as a one way check valve orthe like. In yet other embodiments, a user may use his/her finger toblock the bore 180 in a manner similar to that of a valve. In someembodiments, such as the syringe shown in FIG. 1B, the bore 180 may becurved or angled so that the bore outlet 181 is located substantially ona side of the piston 155, such as, for example, a top side, a bottomside, or the like. In other embodiments, such as the syringe shown inFIG. 1C, the bore 180′ may be substantially straight and/or linear withthe piston 155. Such a configuration may allow for the bore outlet 181′to be located at or near the thumb piece 160. In some embodiments withthis configuration, the thumb piece 160 may act as the valve to blockthe bore outlet 181′, as previously described herein. In otherembodiments with this configuration, a user may block the bore outlet181′ with an external apparatus, a thumb, and/or the like whilemanipulating the thumb piece 160 at the same time.

FIG. 2A depicts a side view of an alternative syringe, generallydesignated 200, according to an embodiment. Similar to the syringe 100disclosed with respect to FIGS. 1A-1C above, the syringe 200 may includea syringe body 205 having a proximal end 201 and a distal end 202. Insome embodiments, the syringe body 205 may include a first plunger 225disposed therein, the plunger incorporating a first seal 230, aspreviously described herein. A delivery volume 275 may be formed betweenthe distal surface of the first plunger 225 and the tip, as previouslydescribed herein.

In various embodiments, a vacuum chamber 220 may be disposed within thesyringe body 205. In some embodiments, the vacuum chamber 220 may bebounded by a distal wall 240 and a proximal thumb piece 260. In someembodiments, at least a portion of the vacuum chamber 220 may containair that is pressurized to a pressure at or above standard atmosphericair pressure at sea level, as described in greater detail herein. Inother embodiments, at least a portion of the vacuum chamber 220 maycontain air that is pressurized to a pressure below standard atmosphericair pressure at sea level, as described in greater detail herein.

In various embodiments, the first plunger 225 may be mechanicallycoupled via a piston 255 to the second plunger 250. The first plunger225 may generally be disposed at a location inside the syringe body 205,as previously described herein, and further disposed at a location thatis distal to the vacuum chamber 220. In some embodiments, thepositioning of the first plunger 225 and the vacuum chamber 220 maydefine a medial compartment 285 therebetween. Particularly, the medialcompartment 285 may be formed between the proximal surface of the firstplunger 225 and the distal surface of the distal wall 240. In someembodiments, the piston 255 may traverse the medial compartment 285 andextend into the vacuum chamber 220 through the distal wall 240. In someembodiments, the piston 255 may be attached by any means of attachmentto the first plunger 225 and/or the second plunger 250. In someembodiments, the piston 255 may be molded as a portion of the firstplunger 225 and/or the second plunger 250. In some embodiments, thepiston 255 may be detachable from the first plunger 225 and/or thesecond plunger 250. The ability to detach the piston 255 from theplungers 225, 250 may allow for the piston to be used with varyingplungers, thereby increasing compatibility with a wide range of syringesof different sizes and shapes, lowering operating costs, loweringmanufacturing costs, enabling the use pre-filled syringes, and/or thelike.

In various embodiments, the second plunger 250 may be located within thevacuum chamber 220. As in the embodiments depicted herein with respectto FIGS. 1A-1C, the second plunger 250 may be configured to form anairtight seal against an interior surface of the vacuum chamber 220,thereby dividing the vacuum chamber into two compartments. A distalvolume compartment 265 may be created by the space between a distalsurface of the second plunger 250 and the distal wall 240 of the vacuumchamber 220. A proximal volume compartment 270 may be created by thespace between a proximal surface of the second plunger 250 and a distalsurface of the thumb piece 260.

In various embodiments, a second seal 245 may be positioned within thedistal wall 240 around the piston 255 to form an airtight seal aroundthe piston. In some embodiments, the second seal 245 may prevent airfrom entering and/or escaping from the distal volume compartment 265when the piston 255 is actuated. In some embodiments, the distal volumecompartment 265 may be sealed and/or evacuated before the syringe 200 isused.

In optional embodiments, the vacuum chamber 220 may include a vent 235.The vent 235 may generally be an opening within the vacuum chamber 220configured to allow fluid communication of air between an area outsidethe syringe body 205 and the proximal volume compartment 270. The vent235 may be further configured to equalize air pressure within theproximal volume compartment 270 with the outside air pressure, asdescribed in greater detail herein. In some embodiments, the outside airpressure may be about 14.7 psi, or standard atmospheric pressure at sealevel.

As depicted in FIG. 2B, a movable thumb piece 260′ may be used insteadof a vent according to some embodiments. The movable thumb piece 260′may be moved generally distally and/or proximally by any means ofmovement, and is not limited by this disclosure. By way of example only,the movable thumb piece 260′ in the present embodiment may contain aplurality of threads 290 that allow the thumb piece to be screwed intothe vacuum chamber 220. In some embodiments, the thumb piece 260′ may bescrewed over the vacuum chamber 220. In other embodiments, the thumbpiece 260′ may be screwed inside the vacuum chamber 220. The thumb piece260′ may be screwed into a specific depth to obtain a desired pressureinside the proximal volume compartment 270, as will be described ingreater detail herein. To aid in determining the pressure inside theproximal volume compartment 270 a guide 295 may be located on thesyringe 200 to aid a user in determining where to position the thumbpiece 260′. For example, the guide 295 may be a plurality of hash marksprinted on an outside surface of the vacuum chamber 220, wherein eachhash mark is labeled with the pressure that will be achieved by movingthe thumb piece 260′ to that hash mark. In some embodiments, the thumbpiece 260 may incorporate a display that indicates the amount ofadjusted pressure inside the proximal volume chamber 270.

In various embodiments, the syringe 200 may further include any numberof shock absorbing devices (not shown). Specific examples of shockabsorbing devices may include, for example, springs, air cushions,absorbing materials, and/or the like. The shock absorbing devices maygenerally function to ensure a smooth distribution of fluid out of thetip 210 at a constant rate that acts supplementary to the driving forcecause by the difference in pressure, as described in greater detailherein.

FIGS. 3A-3B depict movement of the various components of the syringe 100depicted in FIGS. 1A-1C according to an embodiment. More particularly,FIG. 3A depicts an initial state of the syringe 100. As previouslydescribed herein, a force F may be applied to the thumb piece 160 toforce the piston 155 in a distal direction into the syringe body 105. Asa result, the piston 155 may mechanically force the second plunger 150to move in a distal direction within the vacuum chamber 120.

As described in greater detail herein, the second seal 145 and thesecond plunger 150 may be configured to prevent air from entering theproximal volume compartment 170. In addition, the movement of the secondplunger 150 in a distal direction may increase the volume of theproximal volume compartment 170. In some instances, this combination mayresult in a decrease in pressure in the proximal volume compartment 170where the proximal volume compartment has a pressure greater than orequal to zero. However, in instances where the proximal volumecompartment 170 is a vacuum (thereby having a zero pressure), thiscombination will not change the pressure within the proximal volumecompartment 170. This is due to the ideal gas law, which is representedby Equation (1):

PV=nRT  (1)

where P is the pressure of the gas, V is the volume of the gas, n is theamount of substance of gas (also known as number of moles), T is thetemperature of the gas and R is the ideal, or universal, gas constant,equal to the product of the Boltzmann constant and the Avogadroconstant. To compare different volumes, Equation (1) can be written toreflect the different volumes as follows: P_(—)1V_(—)1=nR_(—)1T_(—)1 andP_(—)2V_(—)2=nR_(—)2T_(—)2. If P1 and P2 are both zero because of thevacuum (zero pressure), then a change in either volume V1, V2 will notchange the results.

Furthermore, the pressure can be written as a function of force, asrepresented by Equation (2):

ΔP=F/A  (2)

where ΔP is the change in pressure, F is the normal force, and A is thearea of the surface on contact. Thus, in an illustrative example, if thepressure P is zero (0 psi), such as in a vacuum, then according toEquation (1), the pressure will not change when other variables change,such as, for example, the volume V. Since the pressure remains the same,the force F that is exerted by the pressure will also remain constantaccording to Equation (2), which allows for a smooth distribution of thefluid from within the delivery volume 175.

Similarly, the movement of the second plunger 150 in a distal directionmay decrease the volume of the distal volume compartment 165. However,due to the location of the vent 135 (or in some embodiments, the bore180), the pressure of the distal volume compartment may equalize withthe outside air pressure (i.e., moving towards about 14.7 psi). As aresult the force F may be active on the second plunger 150 due to theunequal pressure between the pressure of the distal volume compartment165 and the pressure of the proximal volume compartment 170. In someembodiments, the pressure of the distal volume compartment 165 may begreater than the pressure of the proximal volume compartment 170. Inother embodiments, such as those where it is desired to add fluid to thesyringe 100, the pressure of the distal volume compartment 165 may beless than the pressure of the proximal volume compartment 170. In someembodiments, to ensure that the proximal volume compartment has a lowerpressure than the distal volume compartment 165, the proximal volumecompartment may be pre-evacuated prior to movement of the piston 155.The pre-evacuation process may be completed, for example, by attaching avacuum pump or the like to the proximal volume compartment 170 through asealable valve and port (not shown).

In various embodiments, because of the unequal pressure between thedistal volume compartment 165 and the proximal volume compartment 170, adriving force F′ may be active on the vacuum chamber 120. However, sincethe user may maintain force on the thumb piece 160 to keep it in adepressed state, the second plunger 150 may be fixed relative to thesyringe body 105. Accordingly, the pressure difference between thedistal volume compartment 165 and the proximal volume compartment 170may force the vacuum chamber 120 to shift in the distal direction,thereby driving the first plunger 125 in a distal direction towards thedistal end 102 of the syringe body 105. The resulting motion of thefirst plunger 125 may reduce the delivery volume 175, causing the fluidin the delivery volume to exit out the tip 110 at a steady rate. Thoseskilled in the art may appreciate that the driving force F′ on the firstplunger 125 may be due to the pressure difference developed between theproximal volume compartment 170 and the distal volume compartment 165,and may not depend on the user's force on the thumb piece 160. Thoseskilled in the art may also appreciate that the driving force F′ on thefirst plunger 125 may not be due to the position of the second plunger150 relative to the vacuum chamber 120 and/or the syringe body 105, aslong as the second plunger is not located at the proximal end 101 or thedistal end 102 of the syringe body. Furthermore, the driving force F′ onthe first plunger 125 may not be due to the velocity of the secondplunger 150 in moving towards the distal end 102 of the syringe body 105provided that there is only a small amount of friction between thesecond plunger and the vacuum chamber 120. Accordingly, the rate ofmotion of the first plunger 125 may be smooth and may not reflect anypossible unsteady movement from the user. Furthermore, the rate ofdelivery of the fluid from the delivery volume 175 may be adjusted bythe user prior to applying force on the thumb piece 160 by increasing ordecreasing the pressure of the distal volume compartment 165, asdescribed in greater detail herein.

FIGS. 4A-4C depict the effect on the syringe of FIG. 2A when a force Fis applied to the thumb piece 260 according to various embodiments. Insome embodiments, the force F may cause the thumb piece 260 to move in agenerally distal direction. This movement of the thumb piece 260 maycause the vacuum chamber 220 to also travel in a generally distaldirection within the syringe body 205. In some embodiments, the variousvolume compartments 265, 270 may change volume as a result of themovement while the pressure remains the same (i.e., about 14.7 psi inthe proximal volume compartment and zero in the distal volumecompartment), as previously described herein. In some embodiments, theforce F applied to the thumb piece 260 may cause the vacuum chamber 220to move relative to the second plunger 250. The movement of the vacuumchamber 220 may therefore result in an increase in the volume of thedistal volume compartment 265 and a decrease in volume of the proximalvolume compartment 270. In various embodiments, a driving force F′ thatpushes the first plunger 225 towards the distal end 202 of the syringebody 205 may result from the difference of pressure of the proximalvolume compartment 270 (where the pressure is at or near atmosphericpressure, or about 14.7 psi) and the distal volume compartment 265(where the pressure is zero) as described herein. Accordingly, if a userof the syringe 200 provides a sharp force on the thumb piece 260, itwill have no effect on the rate of ejection of fluid from the tip 210because the difference in pressures in the distal volume compartment 265and the proximal volume compartment 270 will continue to remain thesame, even with the distal volume compartment increasing in volume. Inaddition, if a faster rate of ejection of fluid from the tip 210 isdesired, the vent 235 can be covered with a valve or a user's fingerwhile a force is exacted upon the thumb piece 260 to increase thepressure of the proximal volume compartment 270 and alter the drivingforce F′ accordingly.

FIGS. 5A-5C depict the effect on the syringe of FIG. 2B when a force Fis applied to the thumb piece 260′ according to various embodiments. Themovement of the various components of the syringe 200 is substantiallythe same as previously described herein with respect to FIGS. 4A-4C;however, instead of regulating the pressure of the proximal volumecompartment 270 with a vent to increase the rate of distribution offluid, the thumb piece 260′ may be moved to adjust the pressure of theproximal volume compartment. For example, the thumb piece 260′ may bemoved in a proximal direction to decrease the pressure of the proximalvolume compartment 270. Similarly, the thumb piece 260′ may be moved ina distal direction to increase the pressure of the proximal volumecompartment 270. In some embodiments, the thumb piece 260′ may be movedin either direction by twisting the thumb piece in a clockwise directionT or in a counterclockwise direction (not shown). In some embodiments,adjusting the thumb piece 260′ to decrease the pressure in the proximalvolume compartment 270 may decrease the difference in pressure betweenthe proximal volume compartment and the distal volume compartment 265,thereby causing the force on the second plunger 250 to decrease, whichmay cause a slower movement of the second plunger in the distaldirection. Similarly, in some embodiments, adjusting the thumb piece260′ to increase the pressure in the proximal volume compartment 270 mayincrease the difference in pressure between the proximal volumecompartment and the distal volume compartment 265, thereby causing theforce on the second plunger 250 to increase, which may cause a fastermovement of the second plunger in the distal direction.

FIG. 6A depicts a side view of a syringe, generally designated 300,having a vent 335 according to an embodiment. The syringe 300 maygenerally include a syringe body 305 having a hollow lumen 307, aproximal end 301, and a distal end 302 having a tip 310. The syringebody 305 is not limited in shape or size by this disclosure, and may beany shape or size, particularly shapes and sizes of syringe bodiescommonly known by those skilled in the art. In various embodiments, thesyringe body 305 may be substantially cylindrical. In variousembodiments, the syringe body 305 may be about 4 ml to about 20 ml involume. In particular embodiments, the volume of the syringe body 305may be about 4 ml, about 5 ml, about 10 ml, about 15 ml, about 20 ml, orany value or range between any two of these values. In variousembodiments, the syringe 300 may be made of glass, a polymer, a metal, acomposite, and/or the like.

In various embodiments, the hollow lumen 307 may include a plurality ofplungers disposed therein. For example, in the present embodiment, thehollow lumen 307 may have a first plunger 325 and a second plunger 350.However, those skilled in the art will recognize that more than twoplungers may be used without departing from the scope of thisdisclosure. In some embodiments, a vacuum chamber 320 may be disposedwithin the syringe body 305 in contact with the first plunger 325. Invarious embodiments, the first plunger 325 may form a seal against theinterior of the syringe body 305 by means of a first seal 330. In someembodiments, the first seal 330 may be a separate component from thefirst plunger 325, such as, for example, an added O-ring and/or thelike. In these embodiments, the first seal 330 may be fixedly attachedto the first plunger 325 by any means of attachment, includingattachment apparatuses, adhesives, and/or the like, or the first sealmay removably attached to the first plunger. In other embodiments, thefirst seal 330 may be fabricated as a portion of the first plunger 325.In some embodiments, the first seal 330 may be associated with a distalportion of the vacuum chamber 320.

In various embodiments, the second plunger 350 may be disposed withinthe first plunger 325. In some embodiments, the second plunger 350 maybe mechanically activated by a piston 355. The second plunger 350 may beattached to the piston 355 by any means of attachment, including, butnot limited to, any number of clips, fasteners, hooks, adhesives, and/orthe like. In some embodiments, the second plunger 350 may be molded as aportion of the piston 355. In some embodiments, the piston 355 may atleast partially extend out of an opening of the proximal end 301 of thesyringe body 305. In some embodiments, the piston 355 may generallyextend out of the first plunger 325 through a proximal wall 340. Theopening in the proximal wall 340 may be sealed with a second seal 345 tothe piston 355. The second seal 345 may be an air-tight seal around theshaft of the piston 355. In some embodiments, the piston 355 may containa bore therethrough, such as 380 in FIG. 6B or 380′ in FIG. 6C, asdescribed in greater detail herein.

In various embodiments, a proximal portion of the piston 355 may beconnected to a thumb piece 360. The thumb piece 360 may generallyprovide a surface upon which a user's digits or another device applies aforce to move the piston 355 in either a distal or proximal direction.The thumb piece 360 is depicted herein as a generally flat surface;however, those skilled in the art will recognize that the shape and sizeof the thumb piece is not limited by this disclosure, and may includeany number of rings, openings, contoured surfaces, and/or the likewithout departing from the scope of the present disclosure. Personsskilled in the art will also note that the term ‘thumb piece’ is notintended to be limiting; while a thumb may be a preferred digit formanipulating the thumb piece 360, the user may use any digit(s), bodyextremity (such as heel of a hand), or object to manipulate the thumbpiece as described herein. In an illustrative example, a user may presshis/her thumb against the thumb piece 360 to effect distal movement ofthe piston 355 and/or other components of the syringe 300, as describedin greater detail herein. In another illustrative example, a user maygrasp thumb piece 360 with his/her thumb and one or more additionaldigits on his/her hand to proximally draw piston 355 and/or othercomponents the syringe 300.

Similar to the first plunger 325 described herein, in variousembodiments, the second plunger 350 may form an airtight seal against aninterior surface of the vacuum chamber 320, thereby dividing the vacuumchamber into two volume compartments. A distal volume compartment 365may be created by the space between a distal surface of the secondplunger 350 and a distal end of the vacuum chamber 320. A proximalvolume compartment 370 may be created by the space between a proximalsurface of the second plunger 350 and a distal surface of the proximalwall 340 of the vacuum chamber 320.

In various embodiments, the vacuum chamber 320 may be detachable fromthe first plunger 325. The ability to detach the vacuum chamber 320 fromthe first plunger 325 may allow for use of vacuum chambers that vary insize and shape, thereby increasing compatibility with a wide range offorces to allow for varying pressures and flow rates, as described ingreater detail herein.

In various embodiments, the vacuum chamber 320 may include a vent 335.The vent 335 may generally be an opening within the vacuum chamber 320and/or a bore through the shaft of piston 355 to allow fluidcommunication of air between the proximal volume compartment 370 and anarea outside the syringe body 305. In some embodiments, thecommunication between the vent 335 and the area outside the syringe body305 may be along a path extending through the proximal wall 340.

In various embodiments, a fluid aspiration volume 375 may be definedwithin the syringe body 305. In some embodiments, the fluid aspirationvolume 375 may be defined as the space that is located distally to thefirst plunger 325. In some embodiments, the fluid aspiration volume 375may contain a fluid therein. Examples of fluids are not limited by thisdisclosure, and may include, for example, medications, supplements,bodily fluids, contrast media, saline, suspensions of biological cells,and/or the like. In some embodiments, fluid contained within the fluidaspiration volume 375 may be aspirated through the tip 310. The tip 310may further be configured to be connected to additional elements, suchas, for example, needles, tubes, nozzles, and/or the like for aspirationof the fluid. It may be appreciated that the first seal 330 may beconfigured to prevent air transfer from either outside the syringe body305 or the vacuum chamber 320 from entering the aspiration volume 375.Similarly, the first seal 330 may be configured to prevent air and/orfluid from escaping the aspiration volume 375 into the vacuum chamber320 and/or the remainder of the syringe body 305. The volume of theaspiration volume 375 may be determined by the distance between thefirst plunger 325 and the distal end 302 of the syringe body 305, aswell as the circumference of the syringe body 305.

In various embodiments, one or more finger guards 315 may be positionedat a location that is generally located at or near the proximal end 301of the syringe body 305. In some embodiments, the finger guards 315 maygenerally be located on an outside surface of the syringe body 305 andmay generally extend from the outside surface of the syringe body. Insome embodiments, the finger guards 315 may act to provide stability tothe syringe 300 during operation. In some embodiments, a user may usethe finger guards 315 to prevent movement of the syringe 300 duringoperation. In some embodiments, the user may use the finger guards 315to prevent the syringe 300 from slipping out of the user's hand. In someembodiments, the user may use the finger guards 315 to protect theuser's fingers. In some embodiments, the finger guards 315 may act as astopping device to prevent the piston 355 from moving further distallyinside the syringe body 305. The shape and size of the finger guards 315are not limited by this disclosure, and may be any shape and/or sizeknown in the art. Specific examples of shapes may be ring shaped, wedgeshaped, and/or the like.

In various embodiments, as depicted in FIGS. 6B and 6C, the bore 380,380′ may be used in lieu of the vent 335 (FIG. 6A). In some embodiments,the bore 380, 380′ may extend through at least a portion of the piston355 and/or the second plunger 350. In some embodiments, the bore 380,380′ may be configured to allow air from outside the syringe 300 toenter and/or escape the vacuum chamber 320, such as proximal volumecompartment 370, effectively regulating by increasing and/or decreasingthe pressure of air inside the vacuum chamber 320. In some embodiments,the bore 380 may include a bore outlet 381 containing a valve and/or thelike to assist in regulation of air pressure inside the vacuum chamber320. In some embodiments, the valve may be incorporated within the thumbpiece 360. In other embodiments, the valve may be a separate element,such as a one way check valve or the like. In yet other embodiments, auser may use his/her finger to block the bore 380 in a manner similar tothat of a valve. In some embodiments, such as the syringe shown in FIG.6B, the bore 380 may be curved or angled so that the bore outlet 381 islocated substantially on a side of the piston 355, such as, for example,a top side, a bottom side, or the like. In other embodiments, such asthe syringe shown in FIG. 6C, the bore 380′ may be substantiallystraight and/or linear with the piston 355. Such a configuration mayallow for the bore outlet 381′ to be located at or near the thumb piece360. In some embodiments with this configuration, the thumb piece 360may act as the valve to block the bore outlet 381′, as previouslydescribed herein. In other embodiments with this configuration, a usermay block the bore outlet 381′ with an external apparatus, a thumb,and/or the like while manipulating the thumb piece 360 at the same time.

FIG. 7A depicts a side view of an alternative syringe, generallydesignated 400, according to an embodiment. Similar to the syringe 300disclosed with respect to FIGS. 6A-6C above, the syringe 400 may includea syringe body 405 having a proximal end 401 and a distal end 402. Insome embodiments, the syringe body 405 may include a first plunger 425disposed therein, the plunger incorporating a first seal 430. Anaspiration volume 475 may be formed between the distal surface of thefirst plunger 425 and the tip 410.

In various embodiments, a vacuum chamber 420 may be disposed within thesyringe body 405. In some embodiments, the vacuum chamber 420 may bebounded by a distal wall 440 and a proximal thumb piece 460. In someembodiments, at least a portion of the vacuum chamber 420 may containair that is pressurized to a pressure at or above standard atmosphericair pressure at sea level, as described in greater detail herein. Inother embodiments, at least a portion of the vacuum chamber 420 maycontain air that is pressurized to a pressure below standard atmosphericair pressure at sea level (i.e., a full or partial vacuum), as describedin greater detail herein.

In various embodiments, the first plunger 425 may be mechanicallycoupled via a piston 455 to a second plunger 450. The first plunger 425may generally be disposed at a location inside the syringe body 405, aspreviously described herein, and further disposed at a location that isdistal to the vacuum chamber 420. In some embodiments, the positioningof the first plunger 425 and the vacuum chamber 420 may define a medialcompartment 485 therebetween. Particularly, the medial compartment 485may be formed between the proximal surface of the first plunger 425 andthe distal surface of the distal wall 440. In some embodiments, thepiston 455 may traverse the medial compartment 485 and extend into thevacuum chamber 420 through the distal wall 440. In some embodiments, thepiston 455 may be attached by any means of attachment to the firstplunger 425 and/or the second plunger 450. In some embodiments, thepiston 455 may be molded as a portion of the first plunger 425 and/orthe second plunger 450. In some embodiments, the piston 455 may bedetachable from the first plunger 425 and/or the second plunger 450. Theability to detach the piston 455 from one or both of the plungers 425,450 may allow for the piston to be used with varying plungers, therebyincreasing compatibility with a wide range of syringes of differentsizes and shapes, lowering operating costs, lowering manufacturingcosts, enabling the use pre-filled syringes, and/or the like.

In various embodiments, the second plunger 450 may be located within thefirst plunger 425. As in the embodiments depicted herein with respect toFIGS. 6A-6C, the second plunger 450 may be configured to form anairtight seal against an interior surface of the vacuum chamber 420,thereby dividing the vacuum chamber into two compartments. A distalvolume compartment 465 may be created by the space between a distalsurface of the second plunger 450 and the distal wall 440 of the vacuumchamber 420. A proximal volume compartment 470 may be created by thespace between a proximal surface of the second plunger 450 and a distalsurface of the thumb piece 260.

In various embodiments, a second seal 445 may be positioned within thedistal wall 440 around the piston 455 to form an airtight seal aroundthe piston. In some embodiments, the second seal 445 may prevent airfrom entering and/or escaping from the proximal volume compartment 470when the piston 455 is actuated. In some embodiments, the proximalvolume compartment 470 may be sealed and/or evacuated before the syringe400 is used.

In optional embodiments, the vacuum chamber 420 may include a vent 435.The vent 435 may generally be an opening within the vacuum chamber 420configured to allow fluid communication of air between an area outsidethe syringe body 405 and the distal volume compartment 465. The vent 435may be further configured to equalize air pressure within the distalvolume compartment 465 with the outside air pressure through a secondvent 436 extending through the syringe body 405. In some embodiments,the outside air pressure may be about 14.7 psi, or standard atmosphericpressure at sea level.

As depicted in FIG. 7B, a movable thumb piece 460′ may be used insteadof a vent according to some embodiments. The movable thumb piece 460′may be moved generally distally and/or proximally by any means ofmovement, and is not limited by this disclosure. By way of example only,the movable thumb piece 460′ in the present embodiment may contain aplurality of threads 490 that allow the thumb piece to be screwed intothe vacuum chamber 420. In some embodiments, the thumb piece 460′ may bescrewed over the vacuum chamber 420. In other embodiments, the thumbpiece 460′ may be screwed inside the vacuum chamber 420. The thumb piece460′ may be screwed into a specific depth to obtain a desired pressureinside the distal volume compartment 465, as will be described ingreater detail herein. To aid in determining the pressure inside thedistal volume compartment 465, a guide 495 may be located on the syringe400 to aid a user in determining where to position the thumb piece 460′.For example, the guide 495 may be a plurality of indicia, such as hashmarks, printed on an outside surface of the vacuum chamber 420, whereineach hash mark is labeled with the vacuum that will be achieved duringaspiration by moving the thumb piece 460′ to that hash mark. In someembodiments, the thumb piece 460 may incorporate a display thatindicates the amount of adjusted vacuum inside the proximal volumechamber 470.

In various embodiments, the syringe 400 may further include any numberof shock absorbing devices 500. Specific examples of shock absorbingdevices 500 may include, for example, springs, air cushions, absorbingmaterials, and/or the like. The shock absorbing devices 500 maygenerally function to ensure a smooth distribution of fluid out of thetip 410 at a constant rate that acts supplementary to the driving forcecause by the difference in pressure, as described in greater detailherein. According to various embodiments, such as illustrated in FIGS.7A-7B, piston 455 may further include one or more indicator markings505, such as hash marks or rings, on the shaft located within medialcompartment 485. The indicator markings 505 may allow a user to knowwhen the draw force on shock absorbing device 500, and therefore therate at which the first plunger 425 is withdrawn, exceeds a criticalinfusion rate. Examples of critical infusion rates may correspond to,for example, the maximum reduced pressure that certain biological cellscan withstand before lysing. Thus, for example, the user may proximallywithdraw thumb piece 460′ while monitoring the reduced pressure withinaspiration volume 475 by observing the indicator markings 505 to ensurethat the reduced pressure does not exceed the pressure at which thebiological cells may lyse.

FIGS. 8A-8B depict movement of the various components of the syringe 300depicted in FIGS. 6A-6C according to an embodiment during an aspirationprocess. More particularly, FIG. 8A depicts an initial state of thesyringe 300. As previously described herein, a force F may be applied tothe thumb piece 360 to force the piston 355 in a proximal direction awayfrom the syringe body 305. As a result, the piston 355 may mechanicallyforce the second plunger 350 to move in a proximal direction within thevacuum chamber 320.

As described in greater detail herein, the movement of the secondplunger 350 in a proximal direction may increase the volume of thedistal volume compartment 365 while decreasing the volume of theproximal volume compartment 370. In some instances, this combination mayresult in a decrease in pressure in the distal volume compartment 365where the distal volume compartment 365 has a pressure greater than orequal to zero. However, in instances where the distal volume compartment365 is a vacuum (thereby having a zero pressure), this combination willnot change the pressure within the distal volume compartment 365. Thisis due to the ideal gas law, which is represented by Equation (1):

PV=nRT  (1)

where P is the pressure of the gas, V is the volume of the gas, n is theamount of substance of gas (also known as number of moles), T is thetemperature of the gas and R is the ideal, or universal, gas constant,equal to the product of the Boltzmann constant and the Avogadroconstant. To compare different volumes, Equation (1) can be written toreflect the different volumes as follows: P₁V₁=nR₁T₁ and P₂V₂=nR₂T₂. IfP₁ and P₂ are both zero because of the vacuum (zero pressure), then achange in either volume V₁, V₂ won't change the results.

Furthermore, the pressure can be written as a function of force, asrepresented by Equation (2):

ΔP=F/A  (2)

where ΔP is the change in pressure, F is the normal force, and A is thearea of the surface on contact. Thus, in an illustrative example, if thepressure P is zero (0 psi), such as in a vacuum, then according toEquation (1), the pressure will not change when other variables change,such as, for example, the volume V. Since the pressure remains the same,the force F that is exerted by the pressure will also remain constantaccording to Equation (2), which allows for a smooth aspiration of thefluid into the aspiration volume 375.

Similarly, the movement of the second plunger 350 in a proximaldirection may decrease the volume of the proximal volume compartment370. However, due to the location of the vent 335 (or in someembodiments, the bore 380), the pressure of the proximal volumecompartment 370 may equalize with the outside air pressure (i.e., movingtowards about 14.7 psi). As a result the force F may be active on thesecond plunger 350 due to the unequal pressure between the pressure ofthe distal volume compartment 365 and the pressure of the proximalvolume compartment 370. In some embodiments, the pressure of theproximal volume compartment 370 may be greater than the pressure of thedistal volume compartment 365. In other embodiments, such as those whereit is desired to expel fluid from the syringe 300, the pressure of theproximal volume compartment 370 may be less than the pressure of thedistal volume compartment 365. In some embodiments, to ensure that theproximal volume compartment has a higher pressure than the distal volumecompartment 365, the distal volume compartment 365 may be pre-evacuatedprior to movement of the piston 355. The pre-evacuation process may becompleted, for example, by attaching a vacuum pump or the like to thedistal volume compartment 365 through a sealable valve and port (notshown). According to these embodiments, the second plunger 350 may belocated adjacent to the inner distal wall of vacuum chamber 320.

In various embodiments, because of the unequal pressure between thedistal volume compartment 365 and the proximal volume compartment 370, adriving force F′ may be active on the vacuum chamber 320. However, sincethe user may maintain force on the thumb piece 360 to keep it in awithdrawn state, the second plunger 350 may be fixed relative to thesyringe body 305. Accordingly, the pressure difference between thedistal volume compartment 365 and the proximal volume compartment 370may force the vacuum chamber 320 to shift in the proximal direction,thereby driving the first plunger 325 in a proximal direction toward theproximal end 301 of the syringe body 305. The resulting motion of thefirst plunger 325 may increase the aspiration volume 375, causing thefluid to be aspirated into the aspiration volume 325 through the tip 310at a steady rate. Those skilled in the art may appreciate that thedriving force F′ on the first plunger 325 may be due to the pressuredifference developed between the proximal volume compartment 370 and thedistal volume compartment 365, and may not depend on the user's force onthe thumb piece 360. Those skilled in the art may also appreciate thatthe driving force F′ on the first plunger 325 may not be due to theposition of the second plunger 350 relative to the vacuum chamber 320and/or the syringe body 305, as long as the second plunger is notlocated at the proximal end 301 or the distal end 302 of the syringebody 305. Furthermore, the driving force F′ on the first plunger 325 maynot be due to the velocity of the second plunger 350 in moving towardsthe proximal end 301 of the syringe body 305 provided that there is onlya small amount of friction between the second plunger and the vacuumchamber 320. Accordingly, the rate of motion of the first plunger 325may be smooth and constant since the force on the first plunger 350 isdetermined by the pressure differential between the distal and proximalcompartments of vacuum chamber 329 and not on the rate at which thesecond plunger is withdrawn, and thus may not reflect any possibleunsteady movement from the user. Furthermore, the rate of aspiration ofthe fluid into the aspiration volume 375 may be adjusted by the userprior to applying force on the thumb piece 360 by increasing ordecreasing the pressure of the proximal volume compartment 370, asdescribed in greater detail herein.

FIGS. 9A-9C depict the effect on the syringe of FIG. 7A when a force Fis applied to the thumb piece 460 according to various embodiments. Insome embodiments, the force F may cause the thumb piece 460 to move in agenerally proximal direction. This movement of the thumb piece 460 maycause the vacuum chamber 420 to also travel in a generally proximaldirection within the syringe body 405. In some embodiments, the variousvolume compartments 465, 470 may change volume as a result of themovement while the pressure remains the same (i.e., about 14.7 psi inthe distal volume compartment 465 and substantially zero psi in theproximal volume compartment 470), as previously described herein. Insome embodiments, the force F applied to the thumb piece 460 may causethe vacuum chamber 420 to move relative to the second plunger 450. Themovement of the vacuum chamber 420 may therefore result in an increasein the volume of the proximal volume compartment 470 and a decrease involume of the distal volume compartment 465. In various embodiments, adriving force F′ that pulls the first plunger 425 towards the proximalend 401 of the syringe body 405 may result from the difference ofpressure of the distal volume compartment 465 (where the pressure is ator near atmospheric pressure, or about 14.7 psi) and the proximal volumecompartment 470 (where the pressure is zero psi) as described herein.Accordingly, if a user of the syringe 400 provides a sharp force on thethumb piece 460 in the proximal direction, it will have no effect on therate of aspiration of fluid through the tip 410 because the differencein pressures in the distal volume compartment 465 and the proximalvolume compartment 470 will continue to remain the same, even with theproximal volume compartment 470 increasing in volume. In addition, if afaster rate of aspiration of fluid through the tip 410 is desired, thevent 435 and/or 436 can be covered with a valve or a user's finger whilea force is exacted upon the thumb piece 460 to increase the pressure ofthe distal volume compartment 470 and alter the driving force F′accordingly. After a desired volume of fluid is aspirated into theaspiration volume 475, the syringe 400 is ready for fluid delivery. Thefluid delivery may be effected by driving the thumb piece 460 in adistal direction such that the proximal volume compartment 470 isreduced in volume relative to the distal volume compartment 465 and thefluid is expelled through the tip 410.

FIGS. 10A-10C depict the effect on the syringe of FIG. 7B when a force Fis applied to the thumb piece 460′ according to various embodiments. Themovement of the various components of the syringe 400 is substantiallythe same as previously described herein with respect to FIGS. 9A-9C;however, instead of regulating the pressure of the distal volumecompartment 465 with a vent to increase the rate of distribution offluid, distal volume compartment 465 contains a gas and is sealed to theatmosphere; and the thumb piece 460′ may be moved to adjust the volumeand the pressure of the distal volume compartment 465. For example, thethumb piece 460′ may have a rod extending in the distal direction thatcontacts the second plunger 450 and urges the second plunger in theproximal or distal direction depending on the position of the thumbpiece 460′. For example, the thumb piece 460′ may be moved in a proximaldirection relative to the vacuum chamber 420 to decrease the pressure ofthe distal volume compartment 465. Because the distal volume compartment465 is at a higher pressure relative to the proximal volume compartment470, the second plunger 450 will move in a proximal direction with themovement of the thumb piece 460′. For example, thumb piece 460′ may beconnected to vacuum chamber 420 by a threaded mechanism where thedistal/proximal position of thumb piece 460′ may be adjusted. In someembodiments, the thumb piece 460′ may be moved in either a proximal or adistal direction by twisting the thumb piece 460′ in a clockwisedirection T (FIG. 10B) or in a counterclockwise direction (not shown).In some embodiments, adjusting the thumb piece 460′ to decrease thepressure in the distal volume compartment 465 may decrease thedifference in pressure between the proximal volume compartment 470 andthe distal volume compartment 465, thereby causing the force on thesecond plunger 450 to decrease, which may cause a slower but uniformmovement of the first plunger 425 in the proximal direction. Similarly,in some embodiments, adjusting the thumb piece 460′ move the secondplunger 450 in a distal direction will increase the pressure in thedistal volume compartment 465 and may increase the difference inpressure between the proximal volume compartment 470 and the distalvolume compartment 465. The force on the second plunger 450 increasescorrespondingly, which may cause a faster but uniform movement of thefirst plunger 425 in the proximal direction.

In another embodiment, the thumb piece 460′ may be sealed to the vacuumchamber 420 and may comprise a threaded rod, or an equivalent connectionmeans, extending through thumb piece 460′ and contacting second plunger450, where the proximal end of the threaded rod has means to rotate thethreaded rod in a clockwise or counter-clockwise direction therebymoving the distal end of threaded rod in a distal or proximal direction.In this manner, the distal or proximal movement of the threaded rodresults in a corresponding distal or proximal movement of the secondplunger 450 relative to the vacuum chamber 420 by turning threaded rodin a clockwise or counter-clockwise direction to force second plunger450 in a distal or proximal direction. The distal volume compartment 465may contain a gas such that movement of the threaded rod and the secondplunger 450 adjusts the volume and the pressure of the distal volumecompartment 465. Because the distal volume compartment 465 is at ahigher pressure relative to the proximal volume compartment 470, thesecond plunger 450 will move in a proximal direction when the forceprovided by threaded rod to the second plunger is lessened, for exampleby rotating threaded rod in a counter-clockwise direction. Adjusting thethumb piece 460′ to decrease the pressure in the distal volumecompartment 465 may decrease the difference in pressure between theproximal volume compartment 470 and the distal volume compartment 465,thereby causing the force on the second plunger 450 to decrease, whichmay cause a slower but uniform movement of the first plunger 425 in theproximal direction. Similarly, in some embodiments, adjusting thethreaded rod to move the second plunger 450 in a distal direction, forexample by rotating in a clockwise direction, will increase the pressurein the distal volume compartment 465 and may increase the difference inpressure between the proximal volume compartment 470 and the distalvolume compartment 465. The force on the second plunger 450 increasescorrespondingly, which may cause a faster but uniform movement of thefirst plunger 425 in the proximal direction. It will be understood thatthe rotation direction of thumb piece 460′ or threaded rod may bereversed by reversing the direction of the threads in either the vacuumchamber 420 or thumb piece 460′.

Although various embodiments have been described in detail for thepurpose of illustration, it is to be understood that such detail issolely for that purpose and that the disclosure is not limited to thedisclosed embodiments, but, on the contrary, is intended to covermodifications and equivalent arrangements. For example, it is to beunderstood that this disclosure contemplates that, to the extentpossible, one or more features of any embodiment can be combined withone or more features of any other embodiment.

1. A syringe system comprising: a syringe body comprising a hollow lumenand a distal end, the syringe body being configured to receive a fluidtherein; a vacuum chamber disposed within the hollow lumen of thesyringe body; a first plunger connected to a distal portion of thevacuum chamber within the hollow lumen of the syringe body, the firstplunger forming a first seal against an inner surface of the syringebody and defining a fluid volume between the first plunger and thedistal end of the syringe body; a second plunger disposed within thevacuum chamber, the second plunger forming a second seal against aninner surface of the vacuum chamber and defining a proximal volumecompartment and a distal volume compartment within the vacuum chamber; avent within one of the proximal volume compartment and the distal volumecompartment of the vacuum chamber, wherein the vent is configured toallow communication of air between an area outside the syringe systemand one of the proximal volume compartment and the distal volumecompartment; and a piston affixed to the second plunger and extendingproximally out of the vacuum chamber, the piston configured to move thesecond plunger within the vacuum chamber, thereby altering a volume ofthe proximal volume compartment and a volume of the distal volumecompartment.
 2. The syringe system of claim 1, wherein the ventcomprises a bore extending therethrough the piston and the secondplunger, the bore configured to allow communication of air between anarea outside the syringe system and one of the proximal volumecompartment and the distal volume compartment.
 3. The syringe system ofclaim 2, further comprising a valve configured to regulate an amount ofthe air communicated between the area outside the syringe system and oneof the proximal volume compartment and the distal volume compartment. 4.The syringe system of claim 1, wherein the vent comprises a side ventextending through a wall in one of the proximal volume compartment andthe distal volume compartment of the vacuum chamber, wherein the sidevent is configured to allow communication of air between an area outsidethe syringe system and one of the proximal volume compartment and thedistal volume compartment.
 5. The syringe system of claim 1, furthercomprising a tip at the distal end of the syringe body, wherein the tipis configured to allow fluid from the fluid volume to pass therethroughupon movement of the first plunger.
 6. The syringe system of claim 5,wherein the tip is further configured to attach to one or more tubes,needles, or nozzles for delivery of the fluid to a patient.
 7. Thesyringe system of claim 1, wherein the piston extends proximally out ofthe vacuum chamber through a proximal wall, forming a third seal betweenthe piston and the proximal wall.
 8. The syringe system of claim 1,wherein a force exacted upon the piston in a substantially distaldirection is configured to cause the second plunger to move distallywithin the vacuum chamber, thereby increasing the volume of the proximalvolume compartment and decreasing the volume of the distal volumecompartment, creating a pressure difference between the proximal volumecompartment and the distal volume compartment, which causes the vacuumchamber and the first plunger to move in a distal direction, therebyexpelling the fluid located in the fluid volume through a tip at thedistal end of the syringe body.
 9. The syringe system of claim 1,wherein a force exacted upon the piston in a substantially proximaldirection is configured to cause the second plunger to move proximallywithin the vacuum chamber, thereby increasing the volume of the distalvolume compartment and decreasing the volume of the proximal volumecompartment, creating a pressure difference between the proximal volumecompartment and the distal volume compartment, which causes the vacuumchamber and the first plunger to move in a proximal direction, therebyaspirating the fluid into the fluid volume through a tip at the distalend of the syringe body.
 10. A syringe system comprising: a syringe bodycomprising a hollow lumen and a distal end, the syringe body beingconfigured to receive a fluid therein; a vacuum chamber at leastpartially disposed within the hollow lumen of the syringe body; a firstplunger disposed distally to the vacuum chamber within the hollow lumenof the syringe body, the first plunger forming a seal against an innersurface of the syringe body and defining a fluid volume between thefirst plunger and the distal end of the syringe body; a second plungerdisposed within the vacuum chamber, the second plunger defining aproximal volume compartment and a distal volume compartment within thevacuum chamber; a side vent extending through a wall in one of thedistal volume compartment and the proximal volume compartment of thevacuum chamber, wherein the side vent is configured to allowcommunication of air between an area outside the syringe system and oneof the proximal volume compartment and the distal volume compartment;and a piston extending distally out of the vacuum chamber and connectedto the first plunger and the second plunger, the piston configured tomove the second plunger within the vacuum chamber and the first plungerwithin the syringe body.
 11. The syringe system of claim 10, furthercomprising a tip at the distal end of the syringe body, wherein the tipis configured to allow fluid from the fluid volume to pass therethroughupon movement of the first plunger.
 12. The syringe system of claim 11,wherein the tip is further configured to attach to one or more tubes,needles, or nozzles for delivery of the fluid to a patient.
 13. Thesyringe system of claim 10, wherein a force exacted upon the vacuumchamber in a substantially distal direction is configured to cause thevacuum chamber to move distally within the syringe body, therebydecreasing the volume of the proximal volume compartment and increasingthe volume of the distal volume compartment, creating a pressuredifference between the proximal volume compartment and the distal volumecompartment, which causes the second plunger, the piston, and the firstplunger to move in a distal direction, thereby expelling the fluidlocated in the fluid volume through a tip at the distal end of thesyringe body.
 14. The syringe system of claim 10, wherein a forceexacted upon the piston in a substantially proximal direction isconfigured to cause the second plunger to move proximally within thevacuum chamber, thereby increasing the volume of the distal volumecompartment and decreasing the volume of the proximal volumecompartment, creating a pressure difference between the proximal volumecompartment and the distal volume compartment, which causes the vacuumchamber and the first plunger to move in a proximal direction, therebyaspirating the fluid into the fluid volume through a tip at the distalend of the syringe body.
 15. A syringe system comprising: a syringe bodycomprising a hollow lumen and a distal end having a tip, the syringebody being configured to receive a fluid therein; a vacuum chamber atleast partially disposed within the hollow lumen of the syringe body; afirst plunger disposed distally to the vacuum chamber within the hollowlumen of the syringe body, the first plunger forming a seal against aninner surface of the syringe body and defining a fluid volume betweenthe first plunger and the distal end of the syringe body; a secondplunger disposed within the vacuum chamber, the second plunger defininga proximal volume compartment and a distal volume compartment within thevacuum chamber; a piston extending distally out of the vacuum chamberand connected to the first plunger and the second plunger, wherein thepiston is configured to move the second plunger within the vacuumchamber and the first plunger within the syringe body; and a thumb pieceremovably attached to a proximal portion of the vacuum chamber, whereinthe thumb piece is configured to provide a surface for a user to apply aforce in a substantially axial direction, and wherein the thumb piece isfurther configured to increase and decrease a volume of one of thedistal volume compartment and the proximal volume compartment.
 16. Thesyringe system of claim 15, wherein the thumb piece is configured toincrease and decrease the volume of one of the distal volume compartmentand the proximal volume compartment by screwing into at least a portionof the vacuum chamber.
 17. The syringe system of claim 15, wherein thethumb piece is configured to move in a distal direction, wherein thevacuum chamber is configured to move within the syringe body in responseto movement of the thumb piece, wherein the second plunger, the piston,and the first plunger are configured to move in response to the vacuumchamber moving within the syringe body.
 18. (canceled)
 19. (canceled)20. (canceled)